1. Field of the Invention
The present invention relates to a semiconductor device with integrated circuits comprising superimposed layers provided at different levels on a substrate, the purpose of which is to produce at least one transmission line in such integrated circuits.
2. Description of Related Art
Conventionally, transmission lines through which an electric current passes, for the purpose of interconnecting the components of integrated circuits or for the purpose of producing integrated radiofrequency circuits, are formed by metal microstrips, which may be or are generally situated near a ground plane, at a short distance from the substrate generally consisting of silicon.
Given the small cross sections and, more particularly, the small thicknesses of said metal microstrips, such conventional transmission lines have high electrical losses. Furthermore, given the short distance between the microstrips and the ground planes, the inductance per unit length of these microstrips is small and the resulting capacitance per unit length is high, such that this leads to a low characteristic impedance of the assembly.